Heat distribution system

ABSTRACT

A portable griddle stove has two non-stick cooking surfaces, either of which can withstand being on the underside of the cooking surface in use and the heat applied to the underside surface. A heat shield and heat diffuser control the temperature applied to the underside of the cooking surface by providing radiant heat to the center portion of the cooking surface and cooling the combustion gas diffused to the perimeter of the cooking surface. Secondary air provided through openings in case the and heat shield assist in cooling the combustion gas.

REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 10/153,409, filed May 22, 2002 now abandoned which is acontinuation application of U.S. patent application Ser. No. 09/796,970,filed Mar. 1, 2001, abandoned; which is a divisional application of U.S.patent application Ser. No. 09/371,262 filed Aug. 10, 1999, issued Jul.31, 2001 as U.S. Pat. No. 6,267,047, all of which are incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates to a portable griddle stove, moreparticularly to a portable griddle stove with dual cooking surfaces.

BACKGROUND INFORMATION

Cooking devices used for camping and other outdoor activities are wellknown in the art. For example, The Coleman Company, Inc. of Wichita,Kans. has been manufacturing portable cooking stoves for many years.Such portable cooking stoves include, for example, one or two burnerssupplied with propane by an attachable tank. Such a portable stoveprovides direct flame impingement on the cooking surface placed on theburner, generally a pot or skillet. Direct flame impingement does notpresent a problem in this circumstance as the pot or skillet is designedto withstand the heat from the flames. Even pots or skillets thatinclude a non-stick coating on the cooking surface, such as TEFLON®manufactured by DuPont of Delaware, can be used with the portable stoveas the underside of the pot or skillet is untreated metal that canwithstand the direct flame impingement, whereas a non-stick surfacecould not withstand the high temperature from direct flame impingement.In addition, portable stoves generally do not provide a cooking surfaceand if a cooking surface is provided, the cooking surface is oftentreated with a non-stick coating and thus cannot be reversible as theunderside would then have a non-stick coating that would be damaged fromthe heat.

Another type of portable cooking device is a barbecue grill, whetherfueled by charcoal, natural gas or propane. While a barbecue is oftenportable, it is not suitable for use indoors due to safety reasons andsize limitations. Further, the cooking surface for a barbecue grill isgenerally a metal grill that provides sufficient support for the food tobe cooked while allowing the heat from the charcoal or burners to passdirectly through the grill to cook the food. Barbecue grills generallydo not provide a solid cooking surface such as griddle surface.

There do exist reversible cooking surfaces, such as a cast iron griddlemanufactured by the Lodge Manufacturing Company that provides a castiron plate that can be placed over a heat source such as flames from acampfire, either side of the cast iron plate providing a cooking surfacesuch as a flat surface on one side and a grooved surface on anotherside. Such a plate, however, cannot have a non-stick coating on bothsides of the griddle that would be exposed to high temperatures.

A popular cooking surface that is not suitable for portable or outdooruse is an electric griddle. An electric griddle usually includes anon-stick cooking surface that is heated on its underside by anelectrically heated coil. Such an electric griddle requires a source ofalternating current electrical power that is often not available forconvenient portable or outdoor use, such as when camping or hiking.

Thus, it is desirable to have a portable cooking system that providestwo non-stick cooking surfaces.

SUMMARY OF THE INVENTION

A portable cooking system includes a tube burner and a diffuser disposedabove the tube burner providing radiant heat to the center portion ofthe cooking surface and directing combustion gas towards the perimeterof the cooking surface. A secondary air flow system provides secondaryair to mix with the diffused combustion gas to control the temperatureof the combustion gas impinging on the perimeter of the cooking surface.As a result of the diffuser and the secondary air flow system, thetemperature of the heat applied to the underside of the cooking surfacein use can be controlled to allow the underside surface to have anon-stick coating.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates an exploded view of an exemplary griddle stoveaccording to an embodiment of the present invention.

FIGS. 2A and 2B illustrate exemplary cooking surfaces according to anembodiment of the present invention.

FIG. 3 illustrates an exemplary connection of a venturi assemblyaccording to an embodiment of the present invention.

FIG. 4 illustrates an exemplary ignition system according to anembodiment of the present invention.

FIG. 5 illustrates an exemplary regulator assembly connector accordingto an embodiment of the present invention.

FIG. 6 illustrates an exemplary heat shield assembly according to anembodiment of the present invention.

FIG. 7 illustrates an exemplary case according to an embodiment of thepresent invention.

FIG. 8 illustrates an exemplary opening in a cooking surface accordingto an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As illustrated in FIG. 1, a griddle stove according to an exemplaryembodiment of the present invention includes, for example, a chassis, afuel delivery system, an electronic ignition system, a heat distributionsystem and cooking surfaces. The chassis includes, for example, a case6, leg brackets 3, 4 and handles 7. Handles 7 have, for example,universal design so that a particular handle 7 can be used on either endof the griddle. The particular appearance and structure of handles are amatter of design choice provided that adequate support is provided forthe case 6 and other components of the grill. The leg brackets 3, 4 andhandles 7 are formed of, for example, glass filled nylon, such aspolyester thermoplastic, flame retardant, 30% glass which has high heatproperties and moderate cost, although other suitable material could beused. The leg brackets 3, 4 provide exemplary means to connect thehandles 7 to case 6 and also provide stiffness to the case 6 as well asthermal isolation between the case 6 and the handles 7. Case 6 is formerof, for example, cold rolled steel, draw quality, and can be paintedwith heat-resistant paint if desired. The chassis also providesstructural support for the other components of the griddle as describedbelow.

FIGS. 2A and 2B illustrate two exemplary cooking surfaces 21, 22disposed on opposite sides of griddle 10. Griddle 10 is formed of, forexample, cast aluminum having a non-stick surface coating, such asTEFLON, on cooking surfaces 21 and 22. Griddle 10 can attach to case 6by, for example, a slip fit or other suitable connection means.

Cooking surface 21 includes a series of raised ribs extendingsubstantially the length of cooking surface 21 while cooking surface 22includes a flat cooking area 24 and a series of shorter raised ribsdisposed at an end area of the cooking surface. The configuration of thecooking surfaces 21, 22 are merely illustrative as any desired patterncan be provided on a particular cooking surface. By having two cookingsurfaces 21, 22, the need to carry additional cooking supplies whencamping, such as a griddle for pancakes and a grill or fish or meat, isminimized.

According to an exemplary embodiment of the present invention, griddle10 includes a roughly circular opening 25. Because griddle 10 in anembodiment of the present invention includes two cooking surfaces 21,22, both cooking surfaces 21, 22 can generate grease when in use, suchas from frying bacon. Accordingly, the grease has to be withdrawn fromthe cooking surface to avoid spillage and undesired flare-up as well asdrawing the grease away from the food being cooked. It is preferable forthe grease to drip directly downward into drip tray 1 which is removablyattachable to handle 7. Opening 25 is provided in cooking surfaces 21,22 for waste removal.

As shown in FIG. 1, drip tray 1 connects to handle 7 and extends underthe cooking surface 21, 22 (dimple). The connection between drip tray 1and handle 7 can be via, for example, tabs on drip tray 1 that lock intocorresponding holes in handle 7. Drip tray 1 is made of, for example,the same material as handle 7. To achieve the desired flow of wastethrough opening 25 and into drip tray 1, a series of bumps 26 or othersuitable protrusions are disposed, for example, around the perimeter ofopening 25 which induce the waste flowing through the opening 25 to formdrops and fall directly into drip tray 1 instead of running along theundersurface of griddle 10. The bumps or protrusions 26 provide aspecific path for the liquid to follow through opening 25.

According to an exemplary embodiment of the present invention, not onlycan two different cooking surfaces be provided on a single griddle 10,but also each cooking surface can have a non-stick coating that is notdamaged when the cooking surface not in use is exposed to heat from theheat distribution system. As illustrated in FIG. 1, the heatdistribution system includes, for example, heat shield 13, tube burner15 and heat diffuser 11.

Tube burner 15 is conventional as is known in the art and includes aplurality of openings along two sides to emit the air-fuel mixture to beignited upon emission from the openings of tube burner 15. Tube burner15 may be made of aluminized steel or other suitable material. Heatshield 13 is disposed below tube burner 15 and connected to case 6 forsupport. Heat shield 13 minimizes heat transfer to the case 6 by actingas a radiant shield, thereby allowing safe tabletop temperatures with alow profile. Heat shield 13 can be manufactured of, for example,aluminized steel and could also be aluminum, stainless steel or a platedsteel. The heat shield 13 channels secondary air to tube burner 15 asdescribed below.

Heat diffuser 11 acts as a barrier between the tube burner 15 and theundersurface of the griddle 10 (e.g., the cooking surface 21, 22 not inuse). The heat diffuser 11 prevents, for example, flames from the tubeburner 15 from impinging directly on the non-stick coating on theundersurface of the griddle 10 and spreads the combustion gases towardsthe perimeter of the griddle 10. Heat diffuser 11 can be made of, forexample, stainless steel, such as 430 stainless steel due to the desireto have the diffuser resist corrosion and withstand high temperatures,although cold rolled steel also could be used but may present corrosionproblems.

As illustrated in FIG. 1, heat diffuser 11 has side portions 112 thatextend upwards towards griddle 10 and angle towards the perimeter ofgriddle 10. In addition, the projections 110 on the diffuser 11 areconfigured to form openings 111 between adjacent projections 110 thathave a quasi V-shape. For example, the openings 111 could have anapproximately 8 degree opening.

In operation, combustion gas (e.g., propane ignited upon exit from thetube burner 15) provides a flame that naturally flows upwards towardsthe side portions 112 of heat diffuser 11. By angling side portions 112upwards, the side portions 112 are optimally positioned to receivemaximum heating from the flames. The flames from tube burner 15 heat theside portions 112 of diffuser 11 which in turn provides radiant heattowards the center portion of griddle 10. Thus, there is little, if any,direct flame impingement on the center of griddle 10, the use of radiantheat from diffuser 11 protecting the non-stick coating on theundersurface of griddle 10.

Since the heat generated by the combustion gas is greatest at the centerportion of the griddle 10 and decreases towards the perimeter of thegriddle, the projections 110 of diffuser 11 push the combustion gas awayfrom the center of the griddle 10. Openings 111 between projections 110allow some combustion gas to escape towards the undersurface of griddle10 for heating purposes while the projections 110 push the combustiongas further towards the perimeter of the griddle 10 to achieve evenheating of the entire cooking surface 21, 22 instead of concentratingthe heating in the center portion of the griddle 10.

Even with the projections 110 pushing the combustion gas towards theperimeter of the griddle 10, the combustion gas may not be sufficientlycooled and could damage the non-stick coating on the undersurface of thegriddle 10. Accordingly, in an exemplary embodiment of the presentinvention, a secondary air system is utilized. Referring to FIG. 6, heatshield 13 includes, for example, a center portion 132 and two edgeportions 131, 133 extending from either side of center portion 132 andangled upwards so as to be angled towards burner tube 15 (e.g., see FIG.1). Center portion 132 includes, for example, a series of openings 134disposed below tube burner 15. Openings 134 channel secondary air to thetube burner 15. Some additional air may be available from a gap betweenthe undersurface of griddle 10 and upper portion of case 6 adjacent tothe handle. With no additional airflow to mix with the combustion gas,however, the combustion gas could be sufficiently hot to damage theunderside of the non-stick cooking surface as well as the bottom pan ofthe grill (e.g., a painted surface on the bottom of case 6 could burn).

Accordingly, a secondary air system is utilized according to anexemplary embodiment of the present invention. Edge portions 131, 133 ofheat shield 13 include, for example, openings 135 that provideadditional air flow to cool the combustion gas that is pushed to theperimeter of the griddle 10 by the heat diffuser 11. Openings 135 arearranged to create a flow of air between openings 135 and openings 60 inthe bottom of case 6, as illustrated in FIG. 7. For example, openings134 and 135 in heat shield 13 are arranged offset from openings 60 incase 6 to provide an airflow path. Openings 134 and 135 are generallynot aligned with openings 60 to prevent a direct path for heat radiationto the tabletop or other surface on which the stove is placed. Alignmentof openings could generate a hotspot on the underlying surface andcreate a safety problem.

Accordingly, openings 60 in case 6 and openings 134, 135 in heat shield13 allow fresh air into the grill and can be arranged as a function ofoffset placement of the openings to channel fresh air to predeterminedlocations so, for example, the fresh air interacts with the combustiongas towards the perimeter of the diffuser 11. It is further noted thatby angling the edge portions 131, 133 of heat shield 13 towards tubeburner 13 and the perimeter of griddle 10, the mixing of the secondaryair with the combustion gas not only cools the combustion gas to a safetemperature for interaction with the underside of the cooking surface,but also causes the volume of combustion gas to expand, thus causing thecombustion gas to expand above the heat diffuser 11 to safely heat theperimeter of the cooking surface 21, 22. The combination of the heatdiffuser 11 and heat shield 13 also dilutes the combustion gases to cooland disperse the heat generated by tube burner 15 so as to not harm theunderside cooking surface 21, 22 and provide even heating of the griddle10.

The fuel delivery system includes, for example, a conventional regulatorassembly 14 that connects to a propane tank (not shown), and a venturiassembly 12 connected to a tube burner 15. Fuel is provided, forexample, by a propane tank (not shown) attached to the regulatorassembly 14, such as a portable propane tank manufactured by The ColemanCompany, Inc. of Wichita, Kans. According to an exemplary embodiment ofthe present invention, the regulator assembly 14 connects to the venturiassembly 12 via, for example, spring clip 36. In this case, no clockingof the regulator assembly 14 or threading is required compared to aconventional connection which employs a threaded connection or notch andlock mating between the regulator and the burner tube 15 via the venturiassembly 12.

As illustrated in FIGS. 3 and 5, according to an exemplary embodiment ofthe present invention, venturi assembly 12 is generally cylindrical witha tube mating portion 30 that attaches to the tube burner 15 via, forexample, a slip fit. An alternative connection could be, for example, apress fit or threaded connection. Adjacent to tube mating portion 30 isa center portion 31 including openings 32. Openings 32 allow air to mixwith the fuel that passes through center portion 31. Towards one end ofcenter portion 31, a groove 33 extends around the circumference of thecenter portion 31. Along a portion of the circumference of groove 33,for example 90° of the circumference of groove 33, material iscompletely removed (e.g., a slot is milled) so that an opening extendsaround a portion of the circumference of center portion 31. Accordingly,groove 33 can releasably receive a spring clip 36 having a flat portion37 and cylindrical portion 38, the flat portion 37 being disposed in theopening in groove 33. Flange 34 bears against the backside of cover 8 toprevent venturi assembly 12 from slipping out of tube burner 15. Endportion 35 protrudes through cover 8 to provide the point of connectionfor connector 50 of regulator assembly 14.

As shown in FIG. 5, connector 50 of regulator assembly 14 includes, forexample, hexagonal portion 51 providing a threaded connection to aconnector tube of regulator assembly 14 transporting fuel towards theventuri assembly 12. Adjacent to hexagonal portion 51 is, for example, acylindrical center portion 52. Groove 53 having, for example, a profilededge 53A, is disposed between center portion 52 and gastip 54 and extendthe circumference of center portion 52. Gastip 54 includes, for example,a profiled edge 54A. In an embodiment of the present invention, profilededge 54A forms a lesser angle with respect to horizontal than profilededge 53A.

Thus, in operation gastip 54 of connector 50 is inserted into endportion 35 of venturi assembly 12. When gastip 54 is inserted intoventuri assembly 12, profiled edge 54A engages spring clip 36, which isdisposed in groove 33, the flat portion 37 of spring clip 36 extendingthrough the opening in groove 33. With sufficient force applied toconnector 50, profiled edge 54A passes under spring clip 36 and flatportion 37 engages groove 53 in connector 50. As a result, regulatorassembly 14 is held in place in venturi assembly 12 by spring clip 36.To remove connector 50, force is applied to connector 50 to extract itfrom venturi assembly 12, the force required generally being greater forremovel than insertion due to the steeper edge 53A having to beovercome. According to an exemplary embodiment of the present inventionemploying such a spring clip connection or other similar connection,operation of the portable grill is simplified and the orientation of thefuel tank is no longer relevant. Connector 50 and venturi assembly 12can be made of, for example, brass or plated steel. It still beappreciated by those skilled in the art that the above describedconnection of venturi assembly 12 and connector 50 can be utilized forconnecting other components in a similar manner.

The ignition system according to an exemplary embodiment of the presentinvention is conventional as is known in the art. The ignition systemincludes, for example, an ignition box 16, an electrode 17, apiezoelectric igniter 18 and a grounding strap 5 as illustrated in FIGS.1, 4 and 6. The electrode 17 attaches to the ignition box 16 with, forexample, a screw, forming a spark gap through which a portion of thefuel-air mixture flows. The piezoelectric igniter 18 attaches to thecover 8 with, for example, igniter bracket 9 and screws. The groundingstrap 5 attaches to the cover and provides grounding to the chassis.Button cover 2 may press into the cover to conceal the tip of thepiezoelectric igniter 18.

Thus, according to an exemplary embodiment of the present invention, aportable griddle stove is provided that has two non-stick cookingsurfaces 21, 22, either of which can withstand being on the underside ofthe cooking surface in use and the heat applied to the undersidesurface. A heat shield 13 and heat diffuser 11 control the temperatureapplied to the underside of the cooking surface by providing radiantheat to the center portion of the cooking surface 21, 22 and cooling thecombustion gas diffused to the perimeter of the cooking surface 21, 22.Secondary air provided through openings in case 6 and heat shield 13assist in cooling the combustion gas.

1. A heat distribution system, comprising: a heat shield connected to ahousing; a burner disposed above the heat shield; and a heat diffuserdisposed above the burner, the heat diffuser including a center portiondisposed at least partly directly above the burner and positionedbetween two angled portions, each of the angled portions extending at anangle upward from the center portion.
 2. The heat distribution systemaccording to claim 1, wherein the heat diffuser further comprises aplurality of elongate projections extending outward from each of the twoangled portions so that a gap is formed between each pair of adjacentprojections, the gaps and the elongate projections defining a serratedouter edge of the diffuser.
 3. The heat distribution system according toclaim 2, wherein the center portion is disposed at a level lower than alevel of the plurality of projections.
 4. The heat distribution systemaccording to claim 2 wherein the openings are quasi-V shaped.
 5. Theheat distribution system according to claim 1, further comprising aventuri assembly connected to the heat distribution system and aregulator assembly connected to the venturi assembly.
 6. The heatdistribution system according to claim 5, wherein the venturi assemblyincludes a cylindrical portion having a circumferential groove, aportion of the circumferential groove being removed to form a slot, aspring clip being removably disposed in the groove.
 7. The heatdistribution system according to claim 6, wherein the regulator assemblyincludes a connector having a profiled edge adjacent a circumferentialgroove, the connector releasably engaging the cylindrical portion of theventuri assembly, the profiled edge releasably engaging a flat portionof the spring clip disposed in the slot, the flat portion of the clampalso being disposed in the circumferential groove of the connector. 8.The heat distribution system according to claim 6, wherein the springclip includes a flat portion.
 9. A stove incorporating the heatdistribution system of claim
 1. 10. A heat distribution system,comprising: a tube burner; and a heat diffuser disposed above the tubeburner, the heat diffuser comprising a center portion disposed at leastpartly directly above the tube burner and positioned between two angledportions, each of the two angled portions having a plurality of elongateprojections extending outwardly therefrom so that a gap is formedbetween each pair of adjacent projections the gaps and the elongateprojections defining a serrated outer edge of the diffuser.
 11. The heatdistribution system according to claim 10, wherein the angled portionsare angled upward from the center portion.
 12. The heat distributionsystem according to claim 10, wherein the openings are quasi-V shaped.13. The heat distribution system according to claim 10, furthercomprising a heat shield positioned below the tube burner.
 14. The heatdistribution system according to claim 10, further comprising a venturiassembly connected to the heat distribution system and a regulatorassembly connected to the venturi assembly.
 15. The heat distributionsystem according to claim 14, wherein the venturi assembly includes acylindrical portion having a circumferential groove, a portion of thecircumferential groove being removed to form a slot, a spring clip beingremovably disposed in the groove.
 16. The heat distribution systemaccording to claim 15, wherein the regulator assembly includes aconnector having a profiled edge adjacent a circumferential groove, theconnector releasably engaging the cylindrical portion of the venturiassembly, the profiled edge releasably engaging a flat portion of thespring clip disposed in the slot, the flat portion of the clamp alsobeing disposed in the circumferential groove of the connector.
 17. Theheat distribution system according to claim 15, wherein the spring clipincludes a flat portion.
 18. A stove incorporating the heat distributionsystem of claim
 10. 19. A heat distribution system, comprising: a tubeburner; and a heat diffuser disposed above the tube burner, the heatdiffuser comprising a center portion disposed at least partly directlyabove the tube burner and positioned between two angled portions, eachof the angled portions extending at an angle upward from the centerportion.
 20. The heat distribution system according to claim 19, each ofthe two angled portions having a plurality of elongate projectionsextending outwardly therefrom so that a gap is formed between each pairof adjacent projections, the gaps and the elongate projections defininga serrated outer edge of the diffuser.
 21. The heat distribution systemaccording to claim 20, wherein the openings are quasi-V shaped.
 22. Astove incorporating the heat distribution system of claim 19.